Petrolatum



C. M. LOANE Oct. 31, 1939.

PETROLATUM Filed March 31, 1957 MEL TIA/6 Pom/r (W?) INVENTOR Oarence Mi Loane BY J 2 ATTOR NEY Patented Oct. 31, 1939 UNITED STATES PATENT OFFICE PETROLATUM Clarence M. Loane, Hammond, Ind., assignor to Standard Oil Company, Chicago, 111., a corporation of Indiana This invention relates to an improved petrolatum and the method of obtaining the same.

It is advantageous to employ for many uses petrolatums which are characterized by a low melting point for a given A. S. T. M. penetration. Among such uses is the use of petrolatum in pharmaceutical preparations. The petrolatums in pharmaceutical preparations used for external application should be preferably a petrolatum which is of a relatively low melting point and relatively hard. In addition the petrolatum should not be of a grainy structure but of a fibrous structure and unctuous. It is diilicult to obtain petrolatums having these desirable characteristics from most crude oils, the crude oils of the so-called Pennsylvania type being one of the few sources from which petrolatums of this kind may be obtained. i

It is, therefore, an object of this invention to provide an improved petrolatum having a desirable melting point and-penetration relationship.

It is another object of the present invention to provide a petrolatum which has a low melting point for a given penetration.

A further object of the present invention is to provide a method of preparing an improved petrolatum having a desirable melting point and penetration relationship. I

Other objects and advantages will become apparent from the following description of the invention read in connection with the accompanying drawing which is a chart for evaluating petrolatums from their melting point and penetration relationship.

The melting point and penetration characteristics of a petrolatum are interdependent and vary with various factors such as the amount of oil in the petrolatum, etc. In order to express this relation by a numerical figure an index has been developed which may be determined either graphically or by equation from the determined meltat equal distances parallel to the base or zero line A. The lines to the left of zero line A represent positive values and those to the right negative values. The quality index of any given petrolatum may be obtained by locating the melting point and the penetration point thereof on the chart and noting its position with reference to the diagonal base line. The desirable petrola- 5 turns will have penetrations and melting point values which fall to the left of the base line A. For example, a petrolatum having a melting point of about 107.5 F, and a penetration of 200 will fall on line C at a point W and will have a quality 10 index of +10 while a petrolatum having a melting point of about 137.5 F. and a penetration of 200 will fall on the line B at a point W and have -a quality index of -5.

Quality Index=75.5-0.5 (it) 0.06(y) I in which a: is the melting point and y the penetration of the petrolatum in question. 20

I have found that the quality index of petrolatums of inferior quality can be improved by adding to such petrolatums small amounts of plastic resins obtained by the polymerization of iso-olefins, such as gaseous or liquid olefins containing branched side chains in the molecule; for example, reacting iso-butylene at temperatures of about --40 to -100 F. with a catalyst such as boron fluoride, aluminum chloride, boron chloride, zinc chloride and other gaseous or solid vola- 30 tile halides of the 2nd, 3rd, 5th, 6th and 8th groups of the periodic system. These plastic resin-like products are high molecular weight hydrocarbons having the empirical formula approximately CnH2n and a molecular weight rang- 35 ing from 1000 to 12000.

The preferred method of obtaining this product i is to treatisobutylene at a temperature of about -*F. at atmospheric pressure with about 0.1 to 0.5%by weight of boron fluoride. The isobutylene which is liquid at -80 F. may be held in a vessel surrounded by a refrigerating bath and the boron fluoride added thereto with constant stirring until the desired plastic, viscous resin is produced. The polymerization product may 45 be subsequently freed of boron fluoride by washing, distillation or other suitable means. A purified viscous resin-like polymerization product so obtained is a clear water white product havin a molecular weightt ranging from 1500 to 8000. 50 This product will be hereinafter referred to as the isobutylene polymer resin.

I have found that by adding from 1 to 10% of an isobutylene polymer resin to petrolatums having undesirable melting point-penetration rela- 55 tionships a much improved product is obtained which possesses a better quality index than the petrolatum had before the addition of the isobutylene polymer resin.

The following experiments, by way of illustrating the invention, demonstrates the effectiveness of the isobutylene polymer resin in improving the quality index of petrolatums. In the experiments the same petrolatum and the same 011 were used.

Composition oi mix Pene- Qual' Exp. No. Per- Per- Percent M. P. ity

cent cent isobutylene tration index petrooil polymer latum added resin It will be noted from the above table that in each instance the addition of the isobutylene polymer resin resulted in a product having a relatively lower melting point for a given penetration and correspondingly an increased quality index.

The penetrations in the above experiments were determined by the A. S. T. M. method D21'7-33T. The melting points were determined by the socalled Whiting method. In this method the melting point of petrolatums is determined in a standard sized melting point tube. The melting point tube, made of glass, which is about mm. long with an internal diameter of 5 mm. is constricted to a small diameter about 20 mm. from one end, making the tube on one side of the constriction about 70 mm. long and on the other side about 20 mm. long. The short or 20 mm. long end of the'tube is provided with a mark at which the melting point temperature is taken. This mark is determined by calibration against a standard tube. In making a melting point determination the 20 mm. long end of the tube is filled to the constriction with the petrolatum sample, and the filled end submerged in a water bath. The bath is then so heated that the temperature increases about 2 to 3 F. per minute. As the petrolatum becomes soft and the melting point is approached the petrolatum rises in the tube. The temperature at which the lower end of the petrolatum column reaches the calibration mark on the submerged end of the tube is recorded as the melting point of the petrolatum.

While I have described my invention in connection with a specific embodiment thereof the same is intended to illustrate and not limit the scope thereof, except as defined in the accompanying claims.

I claim:

1. A petrolatum characterized by a low melting point for a given penetration which comprises a petrolatum characterized by a relatively high melting point for a given penetration and from about 1% to about 10% of an isobutylene polymer resin.

2. A petrolatum characterized by a lower melting point for a given penetration which comprises a petrolatum characterized by relatively high melting point for a given penetration and l to 10% of an isobutylene polymer resin having a molecular weight of about 1500 to 8000.

3. A petrolatum characterized by a low melting point for a given penetration which comprises a petrolatum characterized by relatively high melting point for a given penetration and 3 to 5% of an isobutylene polymer resin having a molecular weight of about 1500 to 8000, said isobutylene polymer resin being prepared by reacting isobutylene with boron fluoride at a temperature of about 40 to F.

4. The method of preparing a petrolatum characterized by a low melting point for a given penetration from a petrolatum normally characterized by a relatively high melting point for a given penetration which comprises admixing with the last named petrolatum from about 1% to about 10% of a high molecular weight isoolefin polymer.

5. The method of preparing a petrolatum characterized by a low melting point for a given penetration as described in claim 4 in which the high molecular weight iso-olefin polymer is a polymerization product obtained by treating an isoolefin with a halide at low temperatures.

6. The method of preparing a petrolatum characterized by a low melting point for a given penetration as described in claim 4 in which the high molecular weight iso-olefin polymer is an 0 

